Code yellow: Augustine Volcano rumbling again

Posted: Friday, September 28, 2007

By MICHAEL ARMSTRONGMorris News Service Alaska, Homer News

As Yogi Berra said, it's a case of deja vu all over again. Last Saturday, after a week of unusual earthquake activity near Augustine Volcano, the Alaska Volcano Observatory raised the volcano alert level to advisory and the aviation color code to yellow for the volcano, located about 75 miles to the southwest of Homer.

The warning levels for Augustine were lowered to normal and green in August 2006 after months of activity, including a big throat-clearing blast on Jan. 11, 2006. The warning level was last increased from green to yellow in September 2005 after earthquakes magnitude 1 or more increased from four-to-eight a day to 20-to-35 a day.

Augustine is rumbling far less than two years ago.

"While significant, the current earthquake activity is much less energetic than that which immediately preceded the explosive events in January 2006," the Alaska Volcano Observatory said in a Sept. 22 information release.

AVO scientists have been monitoring Augustine with numerous seismometers, geographic positioning satellite instruments and even Web cams since the 2005-2006 activity.

After the big January 2006 eruptions, a spine of rock extruded from the summit.

"It's possible we're looking at a last little bit of magma coming out," said Stephanie Prejean, a seismologist with the U.S. Geological Survey, Alaska Volcano Observatory, in Anchorage.

GPS instruments on the volcano haven't shown any deformation or ground swelling. That lack of ground movement supports a theory that something bigger will not happen, Prejean said. However, there is an increased danger of rockfalls and avalanches on the volcano, which is why AVO issued the warning.

Augustine is the most active volcano in the Cook Inlet region, with historic eruptions in 2006, 1986, 1976, 1963-64, 1935, 1883 and 1812. The recent micro earthquakes are not unusual.

"It's not unexpected in the context of Augustine's activity in the past," Prejean said.